Like the dumbing down of the iWorks apps, the Photos app is going through a transition so that it can become more than it was, and in a smarter way.
They needed to strip a lot of the old functionality in order to go forward in a new direction. From the hints I'm getting, you're going to like the result. But it may take a while. The full roll out of how Apple is going to handle photos across iOS and OS X may not be complete until sometime in Spring.
Apple has never been afraid to do this. And most of the time, we do forgive them, eventually.
And please, no one had better say the Photos app was great as it was. It's been one of the most complained about apps on iOS. It's due to some love, even if it's tough love.
The iWorks apps, by the way, have nearly all the missing features back, and now play nicely across the web, Mac, and iOS platforms. A win that most of the initial complainers are coming to, grudgingly, admit.
Patience my friend. This too shall pass.